The park, 60 miles north of San Francisco on the eastern edge of Santa Rosa offers miles of trails for hiking, mountain biking, and trail riding.

For wildflower lovers, Trione-Annadel State Park offers a great variety of flowers from early Spring until early Summer, especially on a hike around Lake Ilsanjo. The best months to see the park's wildflowers are April and May, but there are some plants in bloom as early as January and as late as September.

• Dogs are not allowed on trails. Dogs are allowed on a leash under your control only on Channel Drive (a paved road) within the park.
• Model Aircraft (“drones”)/Unmanned Aircraft Systems (UAS)/Glider Use is not allowed in the park per Bay Area District Order No. 660-16-036.
• Electric-Assist or “E-bikes” are considered motorized vehicles and are not allowed in the park.

Fishing Lake Ilsanjo offers excellent fishing for black bass and bluegill. Black bass weighing nine pounds and more have been caught here. A purple plastic worm is a favored bait for the bass, while the bluegill favor garden worms, small crayfish, and grubs. If you are 16 years of age or older, you must have a California fishing license. Ledson Marsh dries up by late August or early September and so no fish are found there.